The use of control apparatus in processes for the production of treated materials has become more and more widespread in recent years. The high cost of labor, the increased incidence of decreased quality and the need for more uniformity in products have been the prime motivating forces behind the switch over.
In the treating of materials, e.g. the coating, impregnation etc. and drying of materials such as paper, cloth etc., it has especially become increasingly desirable to utilize a fully automatic process and U.S. Pat. No. 3,596,071 is directed to a system which approaches such a realization. This patent discloses and claims a method and apparatus for the control of a coater and dryer wherein variables such as moisture content, resin solids concentration, percent resin and percent volatiles are measured and/or computed according to various mathematical formulae. The computed values are then used to control the rate of resins application and the drying rate of the impregnated material. The controls effected by the patentee are varied by the use of analog computers and are not capable of controlling the penetration rate of a resin into a web.